package org.apache.lucene.document;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.*; // for javadoc
import org.apache.lucene.search.ScoreDoc; // for javadoc
import org.apache.lucene.search.Searcher; // for javadoc
import org.apache.lucene.index.IndexReader; // for javadoc

/** Documents are the unit of indexing and search.
 *
 * A Document is a set of fields.  Each field has a name and a textual value.
 * A field may be {@link Fieldable#isStored() stored} with the document, in which
 * case it is returned with search hits on the document.  Thus each document
 * should typically contain one or more stored fields which uniquely identify
 * it.
 *
 * <p>Note that fields which are <i>not</i> {@link Fieldable#isStored() stored} are
 * <i>not</i> available in documents retrieved from the index, e.g. with {@link
 * ScoreDoc#doc}, {@link Searcher#doc(int)} or {@link
 * IndexReader#document(int)}.
 */

public final class Document implements java.io.Serializable {
    List<Fieldable> fields = new ArrayList<Fieldable>();
    private float boost = 1.0f;

    /** Constructs a new document with no fields. */
    public Document() {
    }

    /** Sets a boost factor for hits on any field of this document.  This value
     * will be multiplied into the score of all hits on this document.
     *
     * <p>The default value is 1.0.
     * 
     * <p>Values are multiplied into the value of {@link Fieldable#getBoost()} of
     * each field in this document.  Thus, this method in effect sets a default
     * boost for the fields of this document.
     *
     * @see Fieldable#setBoost(float)
     */
    public void setBoost(float boost) {
        this.boost = boost;
    }

    /** Returns, at indexing time, the boost factor as set by {@link #setBoost(float)}. 
     *
     * <p>Note that once a document is indexed this value is no longer available
     * from the index.  At search time, for retrieved documents, this method always 
     * returns 1. This however does not mean that the boost value set at  indexing 
     * time was ignored - it was just combined with other indexing time factors and 
     * stored elsewhere, for better indexing and search performance. (For more 
     * information see the "norm(t,d)" part of the scoring formula in 
     * {@link org.apache.lucene.search.Similarity Similarity}.)
     *
     * @see #setBoost(float)
     */
    public float getBoost() {
        return boost;
    }

    /**
     * <p>Adds a field to a document.  Several fields may be added with
     * the same name.  In this case, if the fields are indexed, their text is
     * treated as though appended for the purposes of search.</p>
     * <p> Note that add like the removeField(s) methods only makes sense 
     * prior to adding a document to an index. These methods cannot
     * be used to change the content of an existing index! In order to achieve this,
     * a document has to be deleted from an index and a new changed version of that
     * document has to be added.</p>
     */
    public final void add(Fieldable field) {
        fields.add(field);
    }

    /**
     * <p>Removes field with the specified name from the document.
     * If multiple fields exist with this name, this method removes the first field that has been added.
     * If there is no field with the specified name, the document remains unchanged.</p>
     * <p> Note that the removeField(s) methods like the add method only make sense 
     * prior to adding a document to an index. These methods cannot
     * be used to change the content of an existing index! In order to achieve this,
     * a document has to be deleted from an index and a new changed version of that
     * document has to be added.</p>
     */
    public final void removeField(String name) {
        Iterator<Fieldable> it = fields.iterator();
        while (it.hasNext()) {
            Fieldable field = it.next();
            if (field.name().equals(name)) {
                it.remove();
                return;
            }
        }
    }

    /**
     * <p>Removes all fields with the given name from the document.
     * If there is no field with the specified name, the document remains unchanged.</p>
     * <p> Note that the removeField(s) methods like the add method only make sense 
     * prior to adding a document to an index. These methods cannot
     * be used to change the content of an existing index! In order to achieve this,
     * a document has to be deleted from an index and a new changed version of that
     * document has to be added.</p>
     */
    public final void removeFields(String name) {
        Iterator<Fieldable> it = fields.iterator();
        while (it.hasNext()) {
            Fieldable field = it.next();
            if (field.name().equals(name)) {
                it.remove();
            }
        }
    }

    /** Returns a field with the given name if any exist in this document, or
     * null.  If multiple fields exists with this name, this method returns the
     * first value added.
     * Do not use this method with lazy loaded fields or {@link NumericField}.
     * @deprecated use {@link #getFieldable} instead and cast depending on
     * data type.
     * @throws ClassCastException if you try to retrieve a numerical or
     * lazy loaded field.
     */
    @Deprecated
    public final Field getField(String name) {
        return (Field) getFieldable(name);
    }

    /** Returns a field with the given name if any exist in this document, or
      * null.  If multiple fields exists with this name, this method returns the
      * first value added.
      */
    public Fieldable getFieldable(String name) {
        for (Fieldable field : fields) {
            if (field.name().equals(name))
                return field;
        }
        return null;
    }

    /** Returns the string value of the field with the given name if any exist in
     * this document, or null.  If multiple fields exist with this name, this
     * method returns the first value added. If only binary fields with this name
     * exist, returns null.
     * For {@link NumericField} it returns the string value of the number. If you want
     * the actual {@code NumericField} instance back, use {@link #getFieldable}.
     */
    public final String get(String name) {
        for (Fieldable field : fields) {
            if (field.name().equals(name) && (!field.isBinary()))
                return field.stringValue();
        }
        return null;
    }

    /** Returns a List of all the fields in a document.
     * <p>Note that fields which are <i>not</i> {@link Fieldable#isStored() stored} are
     * <i>not</i> available in documents retrieved from the
     * index, e.g. {@link Searcher#doc(int)} or {@link
     * IndexReader#document(int)}.
     */
    public final List<Fieldable> getFields() {
        return fields;
    }

    private final static Field[] NO_FIELDS = new Field[0];

    /**
     * Returns an array of {@link Field}s with the given name.
     * This method returns an empty array when there are no
     * matching fields.  It never returns null.
     * Do not use this method with lazy loaded fields or {@link NumericField}.
     *
     * @param name the name of the field
     * @return a <code>Field[]</code> array
     * @deprecated use {@link #getFieldable} instead and cast depending on
     * data type.
     * @throws ClassCastException if you try to retrieve a numerical or
     * lazy loaded field.
     */
    @Deprecated
    public final Field[] getFields(String name) {
        List<Field> result = new ArrayList<Field>();
        for (Fieldable field : fields) {
            if (field.name().equals(name)) {
                result.add((Field) field);
            }
        }

        if (result.size() == 0)
            return NO_FIELDS;

        return result.toArray(new Field[result.size()]);
    }

    private final static Fieldable[] NO_FIELDABLES = new Fieldable[0];

    /**
    * Returns an array of {@link Fieldable}s with the given name.
    * This method returns an empty array when there are no
    * matching fields.  It never returns null.
    *
    * @param name the name of the field
    * @return a <code>Fieldable[]</code> array
    */
    public Fieldable[] getFieldables(String name) {
        List<Fieldable> result = new ArrayList<Fieldable>();
        for (Fieldable field : fields) {
            if (field.name().equals(name)) {
                result.add(field);
            }
        }

        if (result.size() == 0)
            return NO_FIELDABLES;

        return result.toArray(new Fieldable[result.size()]);
    }

    private final static String[] NO_STRINGS = new String[0];

    /**
     * Returns an array of values of the field specified as the method parameter.
     * This method returns an empty array when there are no
     * matching fields.  It never returns null.
     * For {@link NumericField}s it returns the string value of the number. If you want
     * the actual {@code NumericField} instances back, use {@link #getFieldables}.
     * @param name the name of the field
     * @return a <code>String[]</code> of field values
     */
    public final String[] getValues(String name) {
        List<String> result = new ArrayList<String>();
        for (Fieldable field : fields) {
            if (field.name().equals(name) && (!field.isBinary()))
                result.add(field.stringValue());
        }

        if (result.size() == 0)
            return NO_STRINGS;

        return result.toArray(new String[result.size()]);
    }

    private final static byte[][] NO_BYTES = new byte[0][];

    /**
    * Returns an array of byte arrays for of the fields that have the name specified
    * as the method parameter.  This method returns an empty
    * array when there are no matching fields.  It never
    * returns null.
    *
    * @param name the name of the field
    * @return a <code>byte[][]</code> of binary field values
    */
    public final byte[][] getBinaryValues(String name) {
        List<byte[]> result = new ArrayList<byte[]>();
        for (Fieldable field : fields) {
            if (field.name().equals(name) && (field.isBinary()))
                result.add(field.getBinaryValue());
        }

        if (result.size() == 0)
            return NO_BYTES;

        return result.toArray(new byte[result.size()][]);
    }

    /**
    * Returns an array of bytes for the first (or only) field that has the name
    * specified as the method parameter. This method will return <code>null</code>
    * if no binary fields with the specified name are available.
    * There may be non-binary fields with the same name.
    *
    * @param name the name of the field.
    * @return a <code>byte[]</code> containing the binary field value or <code>null</code>
    */
    public final byte[] getBinaryValue(String name) {
        for (Fieldable field : fields) {
            if (field.name().equals(name) && (field.isBinary()))
                return field.getBinaryValue();
        }
        return null;
    }

    /** Prints the fields of a document for human consumption. */
    @Override
    public final String toString() {
        StringBuilder buffer = new StringBuilder();
        buffer.append("Document<");
        for (int i = 0; i < fields.size(); i++) {
            Fieldable field = fields.get(i);
            buffer.append(field.toString());
            if (i != fields.size() - 1)
                buffer.append(" ");
        }
        buffer.append(">");
        return buffer.toString();
    }
}
